Primary breast augmentation patients have widely varying characteristics of their breast envelope, parenchyma, and adjacent tissues. When preoperative breast implant selection does not specifically address critical soft-tissue parameters individual to each patient, risks of complications increase. Complications that occur from failure to reconcile a patient's wishes for breast size with her individual tissue characteristics include skin stretch and thinning, ptosis, atrophy of parenchyma, implant edge or shell visibility, implant edge or shell palpability, visible traction rippling, "bottoming" deformities, and lateral implant displacement with widening of the intermammary distance. Previous dimensional systems address implant parenchyma base width relative to implant base width, but no published system adequately addresses or attempts to quantitate the third dimension, tissue stretch, that is critical to estimate amount of fill necessary in a wide range of breast and tissue types. This system addresses the tissue characteristics (T) of the envelope (E), the parenchyma (P), and the implant (I), and the dynamics (D) of implant and filler distribution that affect soft tissues. The acronym TEPID summarizes the key factors that determine aesthetic results and occurrence of problems and reoperations following breast augmentation. This simple, efficient, and clinically practical system focuses on only three tissue measurements to estimate implant volume required to fill each patient's existing breast envelope, on the basis of her individual tissue characteristics: base width of the parenchyma, anterior pull skin stretch, and areola- and/or nipple-to-inframammary-fold distance measured under maximal stretch. The surgeon then adjusts initial volume to address differences in degree of skin stretch (anterior pull skin stretch) and contribution of the patient's existing parenchyma to stretched envelope fill, and to address differences in implant dimensions and filler distribution dynamics. To base decisions of implant pocket location on quantifiable soft-tissue coverage thickness, the system measures soft-tissue pinch thickness of the upper pole and at the inframammary fold. Surgeon time required to measure, estimate, and make preoperative implant selection decisions is less than 5 minutes. This system evolved from compiling and reviewing measurements and results from 330 primary breast augmentations from 1996 to 1999, including round and anatomic implant types with smooth shells and two different textured shells. The TEPID system was then used concurrently with the previous dimensional system for patient tissue evaluation and preoperative implant selection in 627 consecutive primary augmentation cases over a 3-year period from January of 1998 to January of 2001. Implant selection that did not comply with the parameters of the system was necessary in only eight cases. The TEPID system is a simple, efficient, and clinically practical method that allows surgeons to base implant selection on clinically quantifiable, individual patient tissue characteristics.